linux-kernel - Re: [PATCH v14 1/7] rust: sync: add `OnceLock`

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <DB1OL0D3DA8K.2MTH0QKQGRQUQ@kernel.org>
Date: Wed, 02 Jul 2025 17:40:05 +0200
From: "Benno Lossin" <lossin@...nel.org>
To: "Alice Ryhl" <aliceryhl@...gle.com>
Cc: "Andreas Hindborg" <a.hindborg@...nel.org>, "Miguel Ojeda"
 <ojeda@...nel.org>, "Alex Gaynor" <alex.gaynor@...il.com>, "Boqun Feng"
 <boqun.feng@...il.com>, "Gary Guo" <gary@...yguo.net>,
 Björn Roy Baron <bjorn3_gh@...tonmail.com>, "Masahiro
 Yamada" <masahiroy@...nel.org>, "Nathan Chancellor" <nathan@...nel.org>,
 "Luis Chamberlain" <mcgrof@...nel.org>, "Danilo Krummrich"
 <dakr@...nel.org>, "Nicolas Schier" <nicolas.schier@...ux.dev>, "Trevor
 Gross" <tmgross@...ch.edu>, "Adam Bratschi-Kaye" <ark.email@...il.com>,
 <rust-for-linux@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
 <linux-kbuild@...r.kernel.org>, "Petr Pavlu" <petr.pavlu@...e.com>, "Sami
 Tolvanen" <samitolvanen@...gle.com>, "Daniel Gomez" <da.gomez@...sung.com>,
 "Simona Vetter" <simona.vetter@...ll.ch>, "Greg KH"
 <gregkh@...uxfoundation.org>, "Fiona Behrens" <me@...enk.dev>, "Daniel
 Almeida" <daniel.almeida@...labora.com>, <linux-modules@...r.kernel.org>
Subject: Re: [PATCH v14 1/7] rust: sync: add `OnceLock`

On Wed Jul 2, 2025 at 5:27 PM CEST, Alice Ryhl wrote:
> On Wed, Jul 2, 2025 at 5:07 PM Benno Lossin <lossin@...nel.org> wrote:
>> On Wed Jul 2, 2025 at 3:18 PM CEST, Andreas Hindborg wrote:
>> > +impl<T: Copy> OnceLock<T> {
>> > +    /// Get a copy of the contained object.
>> > +    ///
>> > +    /// Returns [`None`] if the [`OnceLock`] is empty.
>> > +    pub fn copy(&self) -> Option<T> {
>> > +        if self.init.load(Acquire) == 2 {
>> > +            // SAFETY: As determined by the load above, the object is ready for shared access.
>> > +            Some(unsafe { *self.value.get() })
>> > +        } else {
>> > +            None
>> > +        }
>>
>> The impl can just be:
>>
>>     self.as_ref().copied()
>>
>> Would it make sense for this function to take `self` instead & we make
>> the `OnceLock` also `Copy` if `T: Copy`? Maybe not...
>
> Atomics are not Copy.

Ah right... Yeah it probably also isn't useful.

---
Cheers,
Benno